Thin films made of, for example, polyimide, porphyrin, sexiphenyl, sexithienyl, polytetrafluoroethylene, etc. are known as functional organic materials. These thin films are known to improve functions of films or add new functions when molecules are oriented and aligned in a particular direction. Various techniques for controlling molecular orientation have hence been developed. A technique for analyzing molecular orientation in a thin film is important for making such control on molecular orientation. To analyze molecular orientation in a functional organic material and to accurately grasp an in-plane structure of atoms near a surface of a thin film are important in studies of functional materials and biotechnology.
Fourier transform infrared spectrometry, soft X-ray absorption spectrometry, ultraviolet photoelectron spectrometry, etc. are known as such an analytical method of molecular orientation. It is known as a method capable of more accurate analysis that multiple-angle incidence resolution spectrometry (MAIRS) is capable of analyzing a thin film on a supporting member having a high-refractive index with high accuracy in combination with infrared spectrometry (see Patent Document 1 and Non-Patent Document 1). This method is to obtain, as two independent spectra, transition moments which are respectively parallel and perpendicular to the thin film when spectra of the thin film are measured by absorption spectrometry. In the case of infrared spectrometry, the aforementioned transition moments parallel and perpendicular to the thin film may be said to be oscillations of a functional group parallel and perpendicular to the thin film. In the multiple-angle incidence resolution spectrometry, unpolarized light is incident on the thin film at several angles of incidence. By analyzing transmitted spectra of the unpolarized light, the unpolarized light is converted into an ordinary ray (light having an electric field oscillation perpendicular to the traveling direction of the light) and a virtual ray (light having an electric field oscillation in the traveling direction of the light). Only by comparing the two spectra, it can easily be analyzed how much each functional group is oriented.    Patent Document 1: Japanese Patent Application Kokai Publication No. 2003-90762.    Non-Patent Document 1: Takeshi Hasegawa, “A Novel Optical Technique for Analysis of Surface and Interface Developed by Using Chemometrics”, Journal of the Society for Biotechnology, April 2006, Vol. 84, No. 4, Pages 134 to 137.